Warren,
Ask the people of San Francisco how many people are inconvenienced by a damaged sidewalk. When they were building BART, they tore some of the sidewalks up on Market street and also Battery Street. Only for a day or so until they could get a temporary set up. Two months later they were still not able to use them. Battery Street has the finincial area on it somewhat like Wall street. Those people are not accostomed to walking more than a few feet. However, you are correct that a main highway is a lot more inconvenience. And we have tunnels here. Try getting on BART and then have it go down while you are under the Bay. Really some experience.But now if it is going to be for more than an hour, they have ways for the people to exit the train and walk a few miles through maintenance tunnels between the main ones to get back above ground.
Ron
